Hello from a n00b needing help.
Thread Starter
1st Gear
Joined: Aug 2019
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Hello from a n00b needing help.
I assume you "old timers" on here have a wealth of knowledge about the C5 & l have a question for you.
On startup there's a screeching coming from what seems to be one of the pulleys/bearings.......is it most likely to be the water pump bearing or could it be any one of them?
Also, has anyone had any of the pulley bearings go out on them while travelling & what were the repercussions???
Any help gratefully accepted, as well as a few STFU n00b type comments>>>>>>>>>>>>
On startup there's a screeching coming from what seems to be one of the pulleys/bearings.......is it most likely to be the water pump bearing or could it be any one of them?
Also, has anyone had any of the pulley bearings go out on them while travelling & what were the repercussions???
Any help gratefully accepted, as well as a few STFU n00b type comments>>>>>>>>>>>>
Last edited by querty; Aug 10, 2019 at 02:20 PM.
Instructor
Joined: Sep 2015
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I had this on one of the idlers -- and ended up replacing both idlers and a tensioner. You have 2 belts -- AC, and everything else.
Step 1:
Remove one belt at a time, start the car, and see if the problems stops. this helps you narrow down set of pulleys you are looking at.
Step 2:
with the belt off, Spin them all. they should NOT spin free like a fidget spinner. They should spin a time or 2 and stop. If they spin super easy, the bearings are shot.
You can safely drive the car as with the AC belt removed. You'll only lose AC.
Step 1:
Remove one belt at a time, start the car, and see if the problems stops. this helps you narrow down set of pulleys you are looking at.
Step 2:
with the belt off, Spin them all. they should NOT spin free like a fidget spinner. They should spin a time or 2 and stop. If they spin super easy, the bearings are shot.
You can safely drive the car as with the AC belt removed. You'll only lose AC.
Last edited by ninety6; Aug 10, 2019 at 02:46 PM.
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Le Mans Master
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St. Jude Donor '13-'14-'15
Is it a screething sound or more of a chrippy sound------ A screething sound gould be a bad pulley or an idler pulley However a more of a chirping sound could be a reasult of the IAC idle control valve not working correctly
Does the sound go away after the eng reaches operating temps ? 185 * plus ?
Does the sound go away after the eng reaches operating temps ? 185 * plus ?
Race Director
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From: South Western Ontario
It's likely a bearing in one of the idler pulleys. Remove the accessory belt and run the engine to see if it still does it or not. If it does,then it's one of the AC belt pulleys. If it stops then it's one of the main belt pulleys.
The C5 doesn't have an IAC.
The C5 doesn't have an IAC.
Le Mans Master
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St. Jude Donor '13-'14-'15
Normally the noise goes away after about 75 miles of driving to let the idle fuel trims to "learn out"
If not it will require a tune to correct the idle airflow
Burning Brakes
Joined: Aug 2017
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From: Newark Delaware
Correct -------sorry ----- But the idle air controll is controlled by the elrctronic throttle on a C5--Often times you will get a chripping sound as the ETC is trying to control the idle As mentioned remove the main belt drive temporarily to see if the noise goes away to eliminate any pulley failures ----If it continues to screech It may be in your ETC system ---I have seen this many many times----More so on bolt on ehgines with a CAI or bolt on mods
Normally the noise goes away after about 75 miles of driving to let the idle fuel trims to "learn out"
If not it will require a tune to correct the idle airflow
Normally the noise goes away after about 75 miles of driving to let the idle fuel trims to "learn out"
If not it will require a tune to correct the idle airflow
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St. Jude Donor '13-'14-'15
It screeches from the TB body blade making raid adjustments to airfloe at idle The sound is caused by the TB not allowiing enough airflow and the sound is coming from squeezing the airflow in a low throtlte position
There is a Bulliten form FAST intakes that says this is a commom problem with their intakes---However their sound in caused by a restrition on their manifold that again sqeezes the airflow and is a simple fix
If you are using a GM intake--- this could be similar to what Fast says is their issue
If you have tuning software or take it to a tuner----Have him temporarily TURN OFF your LTFT corrections--and if it is a airflow squeeze problem it will go away imediately then you know where it is coming from
I had this same issue both on my 98 and 02 C5's that were heavily modded----
PS the most common fix is to ADD more idle airlow --In both P/N and in gear I would start by adding 20% to both
If you go too far you will get a "hanging idle" then simplt back off some until correct
There is a Bulliten form FAST intakes that says this is a commom problem with their intakes---However their sound in caused by a restrition on their manifold that again sqeezes the airflow and is a simple fix
If you are using a GM intake--- this could be similar to what Fast says is their issue
If you have tuning software or take it to a tuner----Have him temporarily TURN OFF your LTFT corrections--and if it is a airflow squeeze problem it will go away imediately then you know where it is coming from
I had this same issue both on my 98 and 02 C5's that were heavily modded----
PS the most common fix is to ADD more idle airlow --In both P/N and in gear I would start by adding 20% to both
If you go too far you will get a "hanging idle" then simplt back off some until correct
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From: Anthony TX
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99% probability that you have a bad or going bad tensioner or idler pulley. Just pull the belts as mentioned and see if the noise stops. OR,, You could use a MECHANICS Stethoscope and put it on each pulley / tensioner and narrow it down that way. Its very easy and that Stethoscope is VERY handy for troubleshooting.
Another even LESS cost troubleshooting aid is to obtain a 4 foot piece of vacuum line. Put one end of the line up to your ear and point the other end at the area where the noise is coming from. The end of the hose will let you pin point the source to an area about the size of a silver dollar. You can zero in on the source of the noise with ease!!
That an OLD SCHOOL Mechanics troubleshooting aid!!!!!!!!!!!!!
Bill
Another even LESS cost troubleshooting aid is to obtain a 4 foot piece of vacuum line. Put one end of the line up to your ear and point the other end at the area where the noise is coming from. The end of the hose will let you pin point the source to an area about the size of a silver dollar. You can zero in on the source of the noise with ease!!
That an OLD SCHOOL Mechanics troubleshooting aid!!!!!!!!!!!!!
Bill
